Plants specifically improved for agriculture, horticulture, biomass conversion, and other industries (e.g. paper industry, plants as production factories for proteins or other compounds) can be obtained using molecular technologies. As an example, great agronomic value can result from modulating the size of a plant as a whole or of any of its organs or the number of any of its organs.
Similarly, modulation of the size and stature of an entire plant, or a particular portion of a plant, or growth rate, or seedling vigor allows production of plants better suited for a particular industry. For example, reductions in the height of specific crops and tree species can be beneficial by allowing easier harvesting. Alternatively, increasing height, thickness or organ size, organ number may be beneficial by providing more biomass useful for processing into food, feed, fuels and/or chemicals (see the US Department of Energy website for Energy Efficiency and Renewable Energy). Other examples of commercially desirable traits include increasing the length of the floral stems of cut flowers, increasing or altering leaf size and shape or enhancing the size of seeds and/or fruits. Changes in organ size, organ number and biomass also result in changes in the mass of constituent molecules such as secondary products and convert the plants into factories for these compounds.
Availability and maintenance of a reproducible stream of food and animal feed to feed animals and people has been a high priority throughout the history of human civilization and lies at the origin of agriculture. Specialists and researchers in the fields of agronomy science, agriculture, crop science, horticulture, and forest science are even today constantly striving to find and produce plants with an increased growth potential to feed an increasing world population and to guarantee a supply of reproducible raw materials. The robust level of research in these fields of science indicates the level of importance leaders in every geographic environment and climate around the world place on providing sustainable sources of food, feed, chemicals and energy for the population.
Manipulation of crop performance has been accomplished conventionally for centuries through plant breeding. The breeding process is, however, both time-consuming and labor-intensive. Furthermore, appropriate breeding programs must be specially designed for each relevant plant species.
On the other hand, great progress has been made in using molecular genetics approaches to manipulate plants to provide better crops. Through introduction and expression of recombinant nucleic acid molecules in plants, researchers are now poised to provide the community with plant species tailored to grow more efficiently and produce more product despite unique geographic and/or climatic environments. These new approaches have the additional advantage of not being limited to one plant species, but instead being applicable to multiple different plant species (Zhang et al. (2004) Plant Physiol. 135:615).
Despite this progress, today there continues to be a great need for generally applicable processes that improve forest or agricultural plant growth to suit particular needs depending on specific environmental conditions. To this end, the present invention is directed to advantageously manipulating plant size, organ number, plant growth rate, plant architecture and/or biomass to maximize the benefits of various crops depending on the benefit sought and the particular environment in which the crop must grow, characterized by expression of recombinant DNA molecules in plants. These molecules may be from the plant itself, and simply expressed at a higher or lower level, or the molecules may be from different plant species.